1. Field of the Invention
The present invention relates to computers, and more specifically, to a Input/Output (I/O) path selection based on workload types.
2. Description of Related Art
Today, strong growth of data in enterprises and other types of organizations may require storage devices with larger and larger capacities. Traditionally, structured and unstructured data are managed by different kind of storage technologies. The same applies for transactional data and, e.g., archived data. On one hand there are relatively small amounts of data to be accesses randomly, whereas on the other hand, a large amount of consecutive data may be retrieved. The price erosion of magnetic disks makes it increasingly easier to manage all sorts of data on the same type of physical device. Another aspect is an even more advanced database technology that not only allows an easy management of relational data but also the management of unstructured data like voice, image or video information. These days, magnetic disks—or hard disks or hard files—may also be used to store large repositories of archived data. Given the growing amount of data storable on a magnetic disk, the type of data stored on one magnetic disk becomes much more diverse. Many different types or data may be stored on the same magnetic disk, or simply disk. Comparable aspects apply also to file servers and tape systems.
On the other side, different types of data may require different access optimization techniques in order to guarantee an optimal overall performance of a complete system being comprised of an application, a server, I-O adapters and disks. Workload types have a strong influence on an optional overall performance, e.g., random access to a disk may require another type of optimization compared to a sequential access to larger, consecutive chunks of data.
A problem with mixed workloads using the same path from an application to a disk is related to performance degradation of the path. The problem may be nailed down to the fact that a port of an I/O adapter may not have mixed workload types. Several approaches have been followed in order to compensate the problem of mixed workloads or performance degradation. Document U.S. Pat. No. 7,032,041B2 discloses a method for determining a workload type from an I/O request and subsequently appointing an appropriate path based on whether the I/O request is a sequential request or a random request. Document U.S. Pat. No. 7,134,040B2 discloses a method and a system for selecting a path to a device to use when sending data requests to the device.
However, because of the above-discussed drawbacks and available technology, there may be a need for an optimized access to magnetic disks from applications generating different types of workloads and using modern infrastructure components that utilize existing hardware in an optimal way.